1. Field of the Invention
A process is disclosed for the synthesis of aryl trifluoromethyl ethers by reacting phenol or certain substituted phenols with a perhalomethane and hydrogen fluoride.
2. Relation to the Prior Art
W. A. Sheppard, J. Org. Chem., 29, 1 (1964) discloses the two-step preparation of aryl trifluoromethyl ethers by the reaction of aryl fluoroformates with sulfur tetrafluoride (SF.sub.4). The aryl fluoroformates are prepared in situ from phenols and carbonyl fluoride (COF.sub.2). The hydrogen fluoride generated in this reaction catalyzes the SF.sub.4 reaction. The two-step process is represented by the following reactions: EQU ArOH+COF.sub.2 .sup.100.degree. C. ArOCOF+HF (1) EQU arOCOF+SF.sub.4 .sup.160.degree.-175.degree. C. ArOCF.sub.3 +SOF.sub.2 ( 2)
french Pat. No. 2,214,674 discloses a two-step process of preparation of aryl trifluoromethyl ethers by the reaction of molybdenum hexafluoride (MoF.sub.6) with aryl chlorothioformates. This process is represented by the following reactions: ##STR1##
F. Mathey and J. Bensoam, Tetrahedron Letters, 2253 (1973) discloses the same process of French Pat. No. 2,214,674. The reactant aryl chlorothioformates are prepared from the corresponding phenols by treatment of their sodium salts with thiophosgene as follows: EQU ArOH.fwdarw.ArONa .sup.CSCl.sbsp.s ArOCSCl
N. N. Iarovenko and A. S. Vasil'eva, J. Gen. Chem. USSR 28, 2539 (1958) describe the reaction of phenyl trichloromethyl ether with a mixture of antimony trifluorides (SbF.sub.3) and antimony pentachloride (SbCl.sub.5) to produce phenyltrifluoromethyl ether.
L. M. Yagupolskii, Dokl. Akad. Nauk SSSR, 105. 100 (1955) discloses a process similar to that described in the Iarovenko et al. article for preparing ArOCF.sub.3 where Ar is C.sub.6 H.sub.5, 2--ClC.sub.6 H.sub.4, 4--F.sub.6 C.sub.6 H.sub.4, 2,4--Cl.sub.2 C.sub.6 H.sub.3, 4--CNC.sub.6 H.sub.4, 4--H.sub.2 NC.sub.6 H.sub.4, 4--HO.sub.2 CC.sub.6 H.sub.4 and 4--H.sub.2 NCOC.sub.6 H.sub.4.
British Pat. No. 765,527 claims the process of manufacture of aryl trifluoromethyl ethers by treatment with hydrogen fluoride at elevated temperatures and pressures according to the reaction: EQU ArOCCl.sub.3 +3 HF .sup.120.degree.-220.degree. C. ArOCF.sub.3 +3HCl
U.S. Pat. No. 4,020,112 describes the formation of various fluorinated products, including diaryl ethers, from the reaction of phenols with HF and SF.sub.4. Aryl trifluoromethyl ethers are not among the products of this reaction.